In an application concerning a device for determining the angular position of a rotating shaft, which is disclosed in document DE 39 39 905, an angular position with high resolution and/or an absolute angular position with respect to a fixed part, can be obtained. The device comprises a fixed light source emitting a light beam in the axial direction of the shaft toward a slanted mirror which is integral in rotation with the shaft. The device comprises also at least one ring-shaped sensor which is concentric with the axial direction and on which the reflected light beam hits.
However, a main drawback of such a device is that the positioning of the sensor with respect to the axis needs to be very precise. The costs resulting of such a positioning operation, is very high. The accuracy of the measured values, which is based on the position of a sole light point, is anyway not very precise. The cost of a ring-shaped sensor or multiple sensor arrangement is also very expensive. In addition, such a device cannot be made very small.